Aeration apparatus



April 23, 1940.

A. J. WEINIG AERATION APPARATUS Filed April 4, 193's 2 Sheets-Sheet 1 INVENTOR,

, ATTORNEY.

April 23, 1940. A. J. WElNlG 2,198,143

AERATION APPARATUS Filed April 4, 195a 2 Sheets-Sheet 2 BY m A ORNEY.

Patented Apr. 23, 1940 Arthur J. Weinig, Golden,

Morse Bros. Machinery 0010., assignor to Company, Denver,

0010., a corporation of Colorado AppllcationApril 4, 1938, Serlal No. 199,883

1 Claim.

This invention relates to improvements in flotation apparatus, and more particularly to improved means for aeration of liquid pulp.

Different flotation reagents and. pulps of diiferent characteristics require different types and degrees of aeration for optimum results. Further, different altitudes at which flotation apparatus may be operated may require different types of and means for aeration, even when other factors remain the same.

It is an object of the present invention to provide improved means for aeration, in flotation apparatus, that may be used to vary the degree and type of aeration according to operating conditions, thus providing apparatus of this character that may be sold for general use and that is adaptable to a wide range of operating requirements. f

Other objects and advantages reside in details of design and construction that will be more fully disclosed in the following description and in the drawings wherein;

Figure 1 is a transverse sectional view of apparatus constructed according to the present invention;

Figure 2 is a longitudinal fragmentary sectional view of the same; and

Figure 3 is a sectional view of a laboratory type apparatus built according to the invention. In the drawings, reference character 5 denotes a conventional flotation cell, having a froth discharge lip at 6 and a rotary froth skimmer or,

paddle 1. Above the cell is superstructure 8 that positioned suitable supports a pair of spaced bearings 9, that journal a vertical hollow shaft I 0 that carries an impeller, open type, as shown at l2.

The impeller is of the general design disclosed and claimed in the United States patent to A. J, Weinig, No. 1,998,694, issued April 23, 1935. In the present case it has been shown as constructed of rubber, which feature is not a part of the present invention.

Below the impeller l2, that is provided with vanes l2a, is a disk-like plate 13 having a central opening I; the disk serving to provide a lower closure for a pumping or suction zone l5. The arrangement of the vanes |2a on the under side of the impeller is in group formation. 'Each group performs a distinctive function in the operation of the impeller. One inner group of vanes is arranged radially to serve as pumping or suction vanes and impart a centrifugal component of force to the adjacent pulp thus tending to throw it outwardly from the impeller and at the preferably of the .pressure from a source not shown. A branch same time create a vortex at the center of rotation to aid in sucking air or other gas, down through the hollow shaft in and into the pulp, as indicated by the arrows. Any common means may be used to rotate the shaft.

Another group of vanes is arranged as chords near the periphery of the circular impeller, and these serve to slice across the pulp and to draw it inwardly. Thus a zone of intense agitation is set up at and near the periphery of the impeller 19 and air or other gas coming down through the hollow shaft NJ is thoroughly mixed with the pulp to rise through the quiescent zone above and, with the aid of the reagent, to form froth at the pulp surface and to float valuable constituents in m a most efficient manner.

start, and to facilitate its pumping'action. It

also helps to recirculate pulp through the agitation zone. The feature of the disk l3 is not the invention of the present applicant.

The cell 5 is provided with a discharge opening for the liquid pulp and for unfloated solids therein, at It, that is covered by a hood or compartment II, the discharge of pulp into and through which is governed by the position of a valve element l8, in the compartment, that is operated by mechanism comprising a valve stem or rod l8a, a lever arm or beam is on a flexible fulcrum 20, and a float 2| depending from the lever arm l9 into the liquid pulp.

The valve stem 18a is pivotally and slidably connected with the lever arm l9 at 22. The object of the discharge control is to maintain a predetermined liquid level in the cell and the control means is similar to the apparatus disclosed and claimed in the copending application of A. J. Weinig, Serial No. 8,946, filed March 1,. 1935 for Liquid level regulation apparatus.

Supported by the superstructure 8 is an air header 23 that conducts air or other gas under 50 line or nipple 24 is conductively tapped into the header and the flow of gas therethrough is man'- ually controlled by means such as an angle valve 25 through which the air or gas may pass, thence through a flexible conduit such as a hose 26, into pulp chute, not shown,

an annular chamber 21 between the bearingsS.

Referring particularly to Figure 3, the details of the novel means of introducing air into the hollow shaft ID are clearly illustrated. The chamber 21 surrounds a portion of the shaft III, and annular sealing cups or rings 28 prevent escapeor leakage of the air or gas around the shaft.

An opening 29 is provided through the shaft within the chamber 21 and provides a double inlet to the hollow interior thereof. .A single inlet or more than two may be used. The pressure of the gas is suflicient to overcome the centrifugal influence of the shaft within the chamher, so that gas or air is forced into the hollow shaft and drawn downwardly by the combined influences of its pressure and the suction of the impeller E2. The amount and the pressure of air entering the, pulp thus may be governed according to operating requirements which, as above pointed Tout, may vary. And since the factors entering into efficient flotation are easily disturbed, the control of air is of great importance. Some flotation operations require violent aeration, others effect better results through more gentle aeration.

'A plug 30 is screwed into the upper end of the hollow shaft Hi to close it and prevent escape of air under pressure, therefrom. Under some conditions, the plug 30 may be removed and the valve 25 closed, in which case atmospheric air will be drawn down the shaft and into the pulp by the pumping action of the impeller. At low altitudes where the pressure and the specific gravity of the' atmosphere are relatively high, the compressed air may, under certain conditions be dispensed with, and atmospheric air drawn in. But at higher altitudes, the atmospheric air has been found less satisfactory and air or gas under pressure is usually preferable for optimum results.

Obviously, the novel means for introducin air hereinabove described are very flexible and may be used with any type of flotation apparatus having mechanical agitation and with any closed type impeller. other details of the apparatus and process may vary widely. Pulp may be fed into known means such as a or it can be introduced through a feed compartment at an end wall. The novelty and improved utility of the present the cell 5 by any well invention resides in the improved means for supplying air or any aeration agent to through the impeller under controllable conditions to meet various operating requirements.

Air or gas introduced through a jet at the bottom of a cell, beneath the impeller, as has been done, is not the equivalent of the present means of aeration, because inthe present case, the air is intimately mixed with the liquid in fine bubbles whereas jet air may pass around to the side and avoid the impeller and rise through the liquid in fewer and larger bubbles. The difference may be of utmost importance in the results attained by a flotation operation; In the present case, air coming down through the hollow impeller shaft cannot escape the pumping and churning action of the impeller by which it is introduced into the zone of agitation.

Another advantage in the present construction over the prior art is the elimination of all air pipes entering through the bottom of the tank or elsewhere below the impeller. Such air pipes have the disadvantage of clogging and they are difficult to clean. They have the further disadvantage that they tend to drain a flotation cell when operation ceases. The present construction lends itself readily to cleaning as the hollow interior of the shaft is accessible for rod cleaning of any obstructions. The present construction obviously is more accessible for any service that may be required than is an aeration system located beneath a flotation machine.

What I claim and desire to secure by Letters Patent is:

The combination with aeration apparatus, inclusive of a rotary impeller on a rigid shaft provided with a gas delivery passage to the impeller extending the entire length of the shaft and journalled in two spaced bearings, and having an inlet to said passage intermediate said bearings, of a hollow housing for the bearings providing a-chamber enclosing said inlet, valve control. mechanism to introduce gas under pressure to the impeller during rotation thereof through the intermediary of said inlet and hollow shaft, and removable means for closing the upper open end of said hollow shaft, whereby gas under pressure may be introduced into the hollow shaft when the valve is open and atmospheric air drawn into the shaft when the upper end of the shaft is open and the valve closed.

- ARTHUR J. WEINIG. 

